Electrodeposited reamer tool

ABSTRACT

The present invention relates to an electrodeposited reamer tool (1) for use in precision bore processing. 
     In this electroplated reamer tool (1), a work processing portion (3) in a reamer body is constituted by a finishing portion (4) having a cylindrical outer peripheral surface and a cutting portion (5) provided on the distal end side of the finishing portion (4) and having a tapered configuration, and abrasive grains (6) are electrodeposited on the outer peripheral surfaces of the finishing portion (4) and the cutting portion (5). 
     In the electrodeposited reamer tool (1) is inserted into a prepared hole provided in a work, the prepared hole is enlarged by the cutting portion (5), and the inner surface of the bore is finished by the finishing portion (4). 
     Accordingly, it is possible to form a precision bore of a predetermined inner diameter in a work without preprocessing the prepared hole with precision.

TECHNICAL FIELD

The present invention relates to an electrodeposited reamer tool for usein precision processing of bores.

BACKGROUND ART

As a conventionally employed electrodeposited reamer, for example, alapping reamer disclosed in Japanese Utility Model Laid-Open No.53427/1985 (filed by Takezawa Seiki) is known.

As shown in FIG. 22, as for the aforementioned reamer A, a workprocessing portion C provided at an end portion of a reamer body (basemetal) B is formed cylindrically over its entire length. The arrangementprovided is such that abrasive grains D are electrodeposited on anexternal peripheral surface of this processing portion C, and anunillustrated pressing member sealed in the processing portion C isscrewed in for expanding the diameter by means of a set bolt provided atan end portion so as to set its diameter, thereby obtaining surfaceaccuracy by controlling the electrodeposited abrasive grain size. Itshould be noted that, in the drawing, reference character E denotes aslit formed in the work processing portion C.

With the above-described electrodeposited reamer tool A, however, sinceits portion where the processing abrasive grains are electrodeposited,i.e., the work processing portion C, has a cylindrical shape, asmentioned above, it is impossible to provide a large machining allowancefor a pre-processing hole which is formed in a work.

In addition, with the above-described electrodeposited reamer tool A,since the surface roughness is adjusted by controlling the processingabrasive grain diameter, it is necessary to set to a small dimension themachining allowance of the pre-processing hole which is formed in thework, in conjunction with the improvement of the surface roughness.

Accordingly, in order to effect precision processing of bores by usingthe above-described electrodeposited reamer tool A, it is necessary topreprocess the work with pre-processing bores having dimensionalaccuracy and surface roughness that are close to targets. For thisreason, there has been a drawback in that the process for preprocessingbecomes very complicated.

In view of the above-described situation, it is an object of the presentinvention to provide an electrodeposited reamer tool which is capable ofeffecting precision processing of bores with high efficiency withoutrequiring a complicated preprocessing step.

DISCLOSURE OF THE INVENTION

An electrodeposited reamer tool in accordance with the present inventionis characterized by comprising: a finishing portion having a cylindricalouter peripheral surface; and a cutting portion provided on a distal endside of the finishing portion and having a tapered configuration,wherein abrasive grains are electrodeposited on the outer peripheralsurfaces of the two processing portions, respectively.

In accordance with this arrangement, by inserting the electrodepositedreamer tool into a prepared hole provided in a work, the prepared holeis enlarged by the cutting portion and is concurrently finished to adesired bore diameter by the finishing portion.

Accordingly, in accordance with the above-described electrodepositedreamer tool, it becomes possible to provide a large machining allowancefor the prepared hole, so that it becomes unnecessary to preprocess theprepared hole with precision, and the preprocessing step is henceextremely facilitated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual overall side-elevational view illustrating afirst embodiment of an electrodeposited reamer tool in accordance withthe present invention;

FIG. 2 is a conceptual overall side-elevational view illustrating asecond embodiment;

FIG. 3 is a cross-sectional side view of an essential portion of theelectrodeposited reamer tool of the same;

FIG. 4 is diagram of an end face of an electrodeposited reamer toolillustrating a third embodiment;

FIG. 5 is a side-elevational view of an essential portion of theelectrodeposited reamer tool of the same;

FIG. 6 is a cross-sectional side view of an essential portionillustrating a state in which abrasive grains are electrodeposited on afinishing portion and a cutting portion;

FIG. 7 is a cross-sectional side view of the essential portion subjectedto truing;

FIG. 8 is a cross-sectional side view of an essential portion inaccordance with a fourth embodiment illustrating a state in which theabrasive grains are subjected to truing;

FIG. 9 is a graph illustrating the relationships the between finishingroughness and the processing length;

FIG. 10 is a side-elevational view of an essential portion of anelectrodeposited reamer tool illustrating a fifth embodiment;

FIG. 11 is diagram of an end face of the electrodeposited reamer tool ofthe same;

FIG. 12 is a cross-sectional view taken along the line A--A of FIG. 11;

FIG. 13 is a graph illustrating the relationships between the finishingroughness and the processing length;

FIG. 14 is a cross-sectional side view of an essential portion of anelectrodeposited reamer tool illustrating a sixth embodiment;

FIG. 15 is an overall side-elevational view of a reamer body in theelectrodeposited reamer tool of the sixth embodiment;

FIG. 16 is a cross-sectional view taken along the line A--A of FIG. 15;

FIG. 17 is a cross-sectional view taken along the line B--B of FIG. 15;

FIG. 18 is a cross-sectional view of an essential portion of the reamerbody shown in FIG. 15;

FIG. 19 is a cross-sectional view of the essential portion of theelectrodeposited reamer tool in which an outer peripheral surface of thecutting portion is formed into a rectilinear configuration in an axialsection;

FIG. 20 is a diagram of calculation for determining positions of oilholes;

FIG. 21 is a diagram explaining the name of each portion of a workprocessing portion; and

FIG. 22 is an overall side-elevational view illustrating a conventionalelectrodeposited reamer tool.

BEST MODE FOR CARRYING OUT THE INVENTION

A detailed description of the present invention will be givenhereinunder with reference to the drawings illustrating severalembodiments shown in FIGS. 1 to 21.

In FIG. 1, a first embodiment of an electrodeposited reamer toolaccording to the present invention is shown.

This electrodeposited reamer tool 1 is constructed such that a workprocessing portion 3 of a reamer body 2 is constituted by a finishingportion 4 having a cylindrical outer peripheral surface and a cuttingportion 5 provided on the distal end side of this finishing portion 4and having a tapered configuration.

Both the finishing portion 4 and the cutting portion 5 are formedcoaxially along a central axis of rotation of the reamer body 2, and across section perpendicular to the central axis of rotation shows acircular configuration. In addition, the cutting portion 5 is formed insuch a manner that its proximal end is formed with the same diameter asthe aforementioned finishing portion 4, and its diameter becomesgradually smaller toward the distal end. It should be noted that theouter peripheral surface of the cutting portion 5 is formed to berectilinear in an axial cross section.

Abrasive grains 6 are secured to the outer peripheral surfaces of thefinishing portion 4 and the cutting portion 5 by means ofelectrodeposition.

The abrasive grains 6 electrodeposited on the finishing portion 4 aretrued and have flat cutting blades, while the abrasive grains 6electrodeposited on the cutting portion 5 are not trued and have sharpcutting blades.

In cases where hole processing is effected by means of theelectrodeposited reamer tool 1 having the above-described construction,if the electrodeposited reamer tool 1 is inserted into a prepared holeof a work, the prepared hole is first enlarged by the cutting portion 5.At this time, the cutting portion 5 in the tapered form has a guidingeffect.

Then, if the electrodeposited reamer tool 1 is further inserted, theinner surface of the hole is finished by the finishing portion 4, sothat a hole of a predetermined inner diameter is formed in the work.

That is, with the electrodeposited reamer tool 1 having theabove-described construction, it is possible to form a hole having apredetermined inner diameter in a work without processing a preparedhole with precision.

Meanwhile, the abrasive grains 6 electrodeposited on the finishingportion 4 have flat cutting blades by being subjected to truing, and theinner surface of the diameter enlarged by the cutting portion 5 isground by these flat cutting blades so as to determine the borediameter, and correct surface roughness and roundness, and the like.

In addition, since the abrasive grains 6 electrodeposited on thefinishing portion 4 have flat distal ends, the area of contact with theinner surface of the hole is large, so that even if the feeding speed ofthe reamer tool 1 is increased, the surface roughness of the innersurface of the hole is not deteriorated.

Here, a comparison between a case where hole processing is effected byusing the electrodeposited reamer tool 1 in accordance with the presentinvention and a case where hole processing is effected using aconventional electrodeposited reamer tool is shown in Table 1.

                  TABLE 1                                                         ______________________________________                                                   Conventional Tool                                                                           Tool of the                                                     Roughing Finishing                                                                              Invention                                        ______________________________________                                        Feed mm/rev. 0.25       0.15      2                                           Machining    25         15       100                                          allowance μm/φ                                                         Surface      6 μm         unaffected                                       roughness in                                                                  pre-                                                                          processing                                                                    Surface      3.5 μm  2 μm  2 μm                                      roughness,                                                                    Rmax                                                                          Roundness    5 μm    2 μm  2 μm                                      Cylindricity 5 μm    2 μm  2 μm                                      ______________________________________                                         Processing dimensions: φ25 × 45L                                    Material to be cut: FC25                                                 

As is apparent from this Table, with the electrodeposited reamer tool 1in accordance with the present invention, even if the machiningallowance is made large and the feeding rate is increased, it ispossible to obtain processing accuracy equivalent to that obtained by aconventional tool. In addition, although, with the conventional tool, asurface roughness of 6 μm or thereabouts is required in pre-processing,and one tool is needed in each of the two processes of roughing andfinishing, with the electrodeposited reamer tool in accordance with thepresent invention, the surface roughness in pre-processing does notaffect the processing, and the required accuracy can be attained by onetool.

A second embodiment of the electrodeposited reamer tool in accordancewith the present invention is shown in FIGS. 2 and 3.

As shown in FIG. 3, this electrodeposited reamer tool 10 is constructedsuch that an outer peripheral surface 12a of a cutting portion 12 in awork processing portion 11 is formed on its axial cross section into acurved line, i.e., by being curved, and ceramics such as TiN is coatedon this cutting portion 12. It should be noted that the construction isbasically similar to that of the electrodeposited reamer tool 1 of thefirst embodiment except for the configuration of the outer peripheralsurface of the cutting portion and the arrangement of the ceramiccoating. In FIG. 2, reference numeral 13 denotes a finishing portion;17, a reamer body; 14, abrasive grains of the finishing portion; 15,abrasive grains of the cutting portion; and 16, a ceramic coating.

In cases where bore processing is effected by using the electrodepositedreamer tool 10 having the above-described construction, the frictionalresistance between the cutting portion 12 and the inner peripheralsurface of the prepared hole in the work is reduced by virtue of theaction of the aforementioned ceramics. Accordingly, the generation offrictional heat is suppressed, and it is possible to obviate suchdrawbacks as the cuttings being deposited onto the cutting portion andhence resulting in the enlargement of the processed bore diameter, or aplucking being caused on the processed surface.

In addition, as for the ceramics such as TiN, the adhesive strength ofcuttings is low compared with that of a nickel which is generally usedfor a plating layer for fixing abrasive grains. For this reason, removalof cuttings from chip pockets is facilitated, which also makes itpossible to prevent in advance the enlargement of the processed borediameter and the plucking on the processed surface.

Also, according to results of an experiment, in a case where boreprocessing is effected by using the electrodeposited reamer tool 10 inaccordance with this embodiment, as compared with a case where boreprocessing is effected by using the electrodeposited reamer tool 1 ofthe first embodiment shown before, the surface roughness, roundness, andcylindricity were respectively identical at 2 μm, whereas even when thefeeding rate was increased from 2 mm/rev. to 3 mm/rev., it was possibleto obtain processing accuracy equivalent to that of the electrodepositedreamer tool 1 of the first embodiment. Namely, the processing efficiencycan be increased by 1.5-fold. In this case, the material of the workused in the experiment was FC25, the processing dimensions were φ25×45Lmm, and the peripheral speed was 20 m/min.

FIGS. 4 to 7 illustrate a third embodiment of an electrodeposited reamertool in accordance with the present invention.

An electrodeposited reamer tool 30 is constructed such that a workprocessing portion 32 of a reamer body 31 is constituted by a finishingportion 33 having a cylindrical outer peripheral surface and a cuttingportion 34 provided on the distal end side of this finishing portion 33and having a tapered configuration. Furthermore, formed in the outerperipheral surface of the work processing portion 32 are a plurality ofnotches 32a, 32a, . . . dividing the outer peripheral surface into equalparts and extending along a central axis of the reamer body 31.

Abrasive grains 35 having a relatively small grain size are secured tothe outer peripheral surface of the aforementioned finishing portion 33by means of deposition, while abrasive grains 36 having a greater grainsize than the abrasive grains 35 are secured to the outer peripheralsurface of the cutting portion 34 by means of deposition. It should benoted that in the third embodiment, as shown in FIG. 7, only theabrasive grains 35 electrodeposited on the finishing portion 33 aretrued.

In accordance with the electrodeposited reamer tool 30 having theabove-described construction, the abrasive grains 36 having a greatergrain size on the cutting portion 34 cut off the prepared hole of thework with high efficiency, while the abrasive grains 36 having a smallergrain size on the finishing portion 33 and trued finish the innersurface of the bore smoothly. Incidentally, at the time of boreprocessing, the cuttings are discharged through the notches 32a, 32a, .. . provided on the outer peripheral surface of the work processingportion.

Here, FIG. 9 shows results of a comparison between an electrodepositedreamer tool (referred to Tool No. 1) having #100 CBN abrasive grainssecured on the outer peripheral surfaces of the finishing portion andthe cutting portion, on the one hand, and an electrodeposited reamertool (referred to as Tool No. 2) in which #100 CBN abrasive grains aresecured on the finishing portion and trued and #80 CBN abrasive grainsare secured on the cutting portion, on the other.

As is apparent from FIG. 9, it was found that, as for Tool No. 2, theprocessing length is extended by about 1.5-fold as compared with ToolNo. 1. This is conceivably attributable to the fact that, with Tool No.2 such as the one shown in FIG. 7, i.e., the electrodeposited reamertool 30 in which the abrasive grains 36 having a large grain size aresecured on the cutting portion 34, chip pockets, i.e., gaps between theabrasive grains, are large, so that a loading due to the cuttings isless likely to occur.

Meanwhile, with the electrodeposited reamer tool 30 in accordance withthis embodiment, the abrasive grains 35 of the finishing portion 33perform only the burnishing action, so that the diameter of the tool canbe made smaller than a conventional electrodeposited reamer tool, andthe finishing surface roughness can be improved. In addition, since theabrasive grains 36 of the cutting portion 34 have a large grain size,the machining allowing can be made large, so that a plurality ofmachining processes, such as the insertion of two tools that hashitherto been practiced, can be dispensed with.

In an electrodeposited reamer tool 40 in accordance with a fourthembodiment shown in FIG. 8, abrasive grains 46 having a large grain sizeare secured only on a distal end portion of an outer peripheral surfaceof a cutting portion 44, while abrasive grains 45 having a small grainsize are secured on an outer peripheral surface of the cutting portion44 following the distal end portion thereof as well as on the outerperipheral surface of the finishing portion 43, and only the abrasivegrains 45 secured on the finishing portion 43 are trued. The otherarrangements are basically similar to those of the electrodepositedreamer tool 30 of the third embodiment. Incidentally, the abrasivegrains 45 are #100 CBN abrasive grains, while the abrasive grains 46 are#80 CBN abrasive grains.

Here, if a comparison is made between the above-describedelectrodeposited reamer tool 40 (referred to as Tool No. 3) on the onehand, and Tool No. 1 and Tool No. 2 on the other, it was found that, asfor Tool No. 3, the processing length is extended slightly more thanTool No. 2, as shown in FIG. 9.

The reason for this is conceivably attributable to the fact that sincethe abrasive grains with a large grain size that are located in thevicinity of a boundary between the finishing portion 33 and the cuttingportion 34 are not present, loading is less likely to occur.

Although in this embodiment a description has been given of an examplein which #100 and #80 are used as the CBN abrasive grains, thisselection is an example in which the surface roughness, roundness, andcylindricity are aimed at 2μ, and it goes without saying that variousmodifications are possible depending on the required accuracy.

FIGS. 10 to 20 illustrate a fifth embodiment of an electrodepositedreamer tool in accordance with the present invention.

In this electrodeposited reamer tool 50, a plurality of notches 51a,51a, . . . extending along a central axis thereof in such a manner as todivide an outer peripheral surface of a work processing portion 51having a circular cross section into equal parts are formed in theprocessing portion 51.

In addition, abrasive grains are secured on external peripheral surfacesof a finishing portion 52 and a cutting portion 53 in the workprocessing portion 51 by means of electrodeposition.

Furthermore, in the aforementioned electrodeposited reamer tool 50, anoil supplying passage 54 is provided along a central axis of rotation,and a plurality of oil holes 55, 55, . . . , which communicate betweenthe oil supplying passage 54 and portions of the outer peripheralsurface of the cutting portion 53 wherein the notches 51a are notformed, are formed.

As clearly shown in FIG. 12, the aforementioned oil holes 55 areprovided in such a manner as to extend in a direction of opening fromthe oil supplying passage 54 toward the tip of the tool, i.e., by beinginclined diagonally toward the tip with respect to the central axis ofrotation, and are open substantially in a longitudinal center of theouter peripheral surface of the cutting portion 53.

If bore processing is effected by means of the electrodeposited reamertool 50 having the above-described construction, the cutting portion 53first enlarges a prepared hole provided in a work.

At this time, since the cutting portion 53 handles most of the boreprocessing, the machining load is large, and a loading due to cuttingsis most likely to occur.

However, since a working fluid is supplied to the aforementioned cuttingportion 53 through the oil supplying passage 54 and the oil holes 55,the cuttings adhering to the cutting portion 53 are carried away by thisworking fluid.

In addition, since the oil holes 55 are open in the outer peripheralsurface of the cutting portion 53, the oil holes 55 can apply a constantworking fluid pressure to a processing point. Incidentally, the supplyof the working fluid to the outer peripheral surface at the workprocessing portion 51 other than the work processing point is effectedby the notches 51a from outside the tool 50.

FIG. 13 shows a comparison between the electrodeposited reamer tool 50of this embodiment and a conventional electrodeposited reamer tool notprovided with the oil holes, through a graph on the relationshipsbetween the processing length and the finishing surface roughness. Thegraph shows that, with this embodiment, i.e., the electrodepositedreamer tool provided with the oil holes, since the loading due tocuttings is reduced, the processing length is prolonged before thefinishing surface roughness begins to deteriorate. In other words, withthe tool which is not provided with the oil holes, it is difficult toupgrade the levels of processing conditions owing to the loading causedby the cuttings, but it is possible to upgrade the levels of processingconditions by the provision of the oil holes.

In addition, although it has been difficult to effect electrodepositedreamer processing with respect to materials such as Al and Ni alloys,which produce long cuttings, processing can now be effected by theprovision of the oil holes, although the processing conditions arerestricted.

FIGS. 14 to 18 illustrate a sixth embodiment of an electrodepositedreamer tool in accordance with the present invention.

As shown in FIG. 14, an electrodeposited reamer tool 60 is constructedsuch that a work processing portion 61 is constituted by a finishingportion 62 having a cylindrical outer peripheral surface and a cuttingportion 63 in which its outer peripheral surface is formed into a shapeof R in its axial cross section, abrasive grains 64 beingelectrodeposited on outer peripheral surfaces of both portions 62, 63.The abrasive grains secured on the finishing portion 62 are trued, androughing is effected between points A - B in FIG. 13, medium finishingis effected between points B - C, and finishing is effected subsequentto point C of the trued finishing portion 62.

Meanwhile, as shown in FIGS. 15 - 18, formed in an outer peripheralsurface of a reamer body of the aforementioned electrodeposited reamertool 60 are a plurality of notches 61a, 61a, . . . extending along acentral axis of rotation. In addition, an oil supplying passage 65 isprovided in the electrodeposited reamer tool 60 along the central axisof rotation, and oil holes 66 communicating between the oil supplyingpassage 65 and the outer peripheral surface of the work processingportion 61 are formed. In addition, oil reservoirs 67 in which the oilholes 66 are open are formed in the outer peripheral surface of the workprocessing portion 61.

Here, FIG. 19 illustrates an electrodeposited reamer tool 70 inaccordance with the present invention, wherein the outer peripheralsurface of a cutting portion 72 in a work processing portion 71 isformed into a rectilinear line in its axial cross section.

The work processing portion 71 in this electrodeposited reamer tool 70is divided into the cutting portion 72 for mainly effecting roughing anda finishing portion 73 for effecting finishing. In addition, since thereare invariably variations in the grain size of electrodeposited abrasivegrains 74, the number of abrasive grains which actually act inprocessing is greater between points B - C in a rear half section of thecutting portion 72 than between points A - B in a forward half sectionthereof, and the size of chip pockets becomes smaller to the contrary.The section between these points B - C is important as a portion forhandling processing which corresponds to medium processing, and it isnecessary to permit a smooth shift from roughing (between points A - B)to finishing (subsequent to point C). In order to stabilize theprocessing between points B - C, it is necessary to widen that range.However, this would require an angle of taper to be very small at 1degree or less in terms of the configuration of a taper, so that themanufacture has been difficult, and it has been necessary to provide alarge allowance for tool withdrawal. Furthermore, if the levels ofworking conditions are further upgraded, a loading occurs between pointsB - C owing to the cuttings, so that this loading cannot be sufficientlysuppressed even if oil holes are provided in the cutting portion 72.

In contrast, with the electrodeposited reamer tool 60 of the sixthembodiment, by providing an arrangement, as shown in FIG. 14, in whichthe work processing portion 61 is constituted by the finishing portion62 (subsequent to point C) having the cylindrical outer peripheralsurface and the cutting portion 63 (between points A - C) in which itsouter peripheral surface is formed into the shape of R in its axialcross section, the range of medium finishing in the intermediate section(between points B - C) can be enlarged than the aforementionedelectrodeposited reamer tool 70.

In addition, the number of the abrasive grains 64 and the size of thechip pockets change two-dimensionally from roughing (between points A -B) to finishing (subsequent to point C). Thus, the processing conditionchanges more smoothly than the electrodeposited reamer tool 70, and themore the processing point approaches the point C, the smaller the rateof change and the more stable finishing can be performed.

Here, Table 2 shows a comparison between a case in which bore processingis effected by using the electrodeposited reamer 60 of the sixthembodiment and a case in which bore processing is effected by using theelectrodeposited reamer tool 70 shown in FIG. 19.

                  TABLE 2                                                         ______________________________________                                               Electro-  Electro-                                                            deposited deposited   Processing                                              Reamer Tool 70                                                                          Reamer Tool 60                                                                            Conditions                                       ______________________________________                                        Surface  Ry 2 μm  Ry 1.5 μm                                                                              Processing                                   roughness                        dimensions:                                  Cylindricity                                                                           2 μm     1.2 μm   P21 × 45l                              Roundness                                                                              2 μm     1.3 μm   Material to be                               Straightness                                                                           3 μm/45 mm                                                                             3 μm/45 mm                                                                             cut: FC25                                    Tool life                                                                              32 m        48 m        Feed: 2                                                                       mm/rev.                                                                       Cutting speed:                                                                20 m/min.                                                                     Cutting                                                                       allowance:                                                                    100 μm/φ                              ______________________________________                                    

As is apparent from the foregoing Table, it was found that, inaccordance with the electrodeposited reamer tool 60 of this embodiment,given the same processing conditions, the surface roughness,cylindricity, and roundness can be improved, and the tool life isprolonged by about 1.5-fold that of the electrodeposited reamer tool 70.

Meanwhile, at the time when bore processing is effected by means of theelectrodeposited reamer tool 60, since the working fluid is supplied tothe work processing portion 61 via the oil supplying passage 65, the oilholes 66, and the oil reservoirs 67, the cuttings adhering to the workprocessing portion 61 are carried away, with the result that the loadingof the work processing portion 61 is suppressed.

Here, FIG. 20 is a diagram for calculating the positions at which theoil holes 66 are formed in the electrodeposited reamer tool 60, theabscissas show the radius (mm) of the tip of the tool (base metal),while the ordinates show the length (mm) of each portion from the tip ofthe tool. FIG. 21 is a diagram explaining each portion of the workprocessing portion 61, where it is assumed that

    ______________________________________                                        Machining allowance (radius)                                                                         0.05   mm (t)                                          Average diameter of abrasive                                                                         0.22   mm (d)                                          grains used                                                                   Amount of truing (radius)                                                                            0.055  mm (s)                                          Difference with the radius of                                                                        0.2    mm (p)                                          tool tip                                                                      Radius of tool tip (base metal)                                                                      R                                                      then,                                                                          ##STR1##                                                                     Position of portion A . . .                                                    ##STR2##                                                                     Position of portion B . . .                                                    ##STR3##                                                                     ______________________________________                                    

In the case of a blind bore processing, if it is assumed that theallowance for tool withdrawal is allowed up to 15 mm, it is necessary toprovide 500 mm or less as the radius of the tool tip, R, on the basis ofFIG. 20. If R=500 mm, the portion of the tool for handling roughing andmedium finishing is the range from point (A) on the L - l' curve topoint (B) on the L-curve in FIG. 20. Accordingly, it can be appreciatedthat an optimum position for providing an oil hole is at a position of4-14 mm from the tool tip.

INDUSTRIAL APPLICABILITY

The electrodeposited reamer tool in accordance with the presentinvention can be applied effectively when precision bore processing isperformed on various works.

We claim:
 1. An electrodeposited reamer tool characterized by:afinishing portion having a cylindrical outer peripheral surface; and acutting portion provided on an end side of said finishing portion, anouter peripheral surface in an axial cross section of said cuttingportion being curved so as to have a tapered configuration, whereinabrasive grains are electrodeposited on said outer peripheral surface ofsaid finishing portion and said outer peripheral surface of said cuttingportion, the abrasive grains electrodeposited on said finishing portionare being trued; and wherein abrasive grains having a grain size greaterthan that of said abrasive grains electrodeposited on said outerperipheral surface of said finishing portion are electrodeposited on atleast an end portion of said outer peripheral surface of said cuttingportion.
 2. An electrodeposited reamer tool according to claim 1,wherein said cutting portion is provided with a ceramic coating.
 3. Anelectrodeposited reamer tool according to claim 1, wherein a pluralityof notches extending along a central axis of rotation are formed on saidouter peripheral surfaces of said finishing portion and said cuttingportion.
 4. An electrodeposited reamer tool according to claim 1,wherein there are provided an oil supplying passage extending along acentral axis of rotation and an oil hole communicating between said oilpassage and said outer peripheral surface of said cutting portion.
 5. Anelectrodeposited reamer tool according to claim 4, wherein said oil holeis provided in such a manner as to extend by being inclined diagonallytoward the tip with respect to said central axis of rotation.
 6. Anelectrodeposited reamer tool according to claim 4, wherein an oilreservoir in which said oil hole is open is formed on said outerperipheral surface of said cutting portion.
 7. An electrodepositedreamer tool according to claim 6, wherein said oil hole is formed and alength of said oil reservoir are determined by conditions including adiameter of a prepared hole in a work, a finished diameter, an allowancefor tool withdrawal, and a radius of a tool tip.